Gun perforator



pril 13, 1943.

FIG.

INVENIOR.

Patented Apr. 13'. 1943 GUN ranronaron Robert R. Thompson and Whitman D.

Tex., assignors to Standard Oil De- Houston,

Mounce,

velopment Company, a corporation ofDel'aware Application October 17, 1940, Serial No. 361,514

The present invention is directed to a firing chamber for a bore hole gun and a method for strings. Since the barrel from which the bullet must be projected is necessarily short, the time for developing the projecting pressure is also very short. Consequently, the development of a sumciently high projecting pressure has been one of the major problems in the construction and use of bore hole guns.

The art has almost universally resorted to mechanical means for holding the bullet in place in the barrel until suflicient pressure is developed behind it. The mechanical means has assumed the form of a washer embedded in a recess in the gun barrel and having sufiiciently small internal diameter to form a stop for a fiange on the inner end of the bullet, whereby the bullet is not projected until sufiicient pressure is built up behind it to either shear off the flange on the rear end of the bullet or shear ofi the washer.

The provision of this washer, of course, necesvsitatesthe making of the barrel in parts so'that, after a shot, the washer can be replaced. This has been found unsatisfactory for the reason that the straih exerted on the parts is such as to distort the threads connecting them and thereby limit the number of times the parts can be separated and reassembled.

The'present invention is based on the discovery that the use of mechanical restraining means can be avoided by the simple expedient of using the bullet asa ram for compressing the powder into the powder chamber. That is to say, in the practice of the present invention the barrel is filled with powder and then the bullet is forced into the barrel by sufiicient pressure to compress the powder into the firing chamber at the rear end of the barrel. It has been found that, as a result otthis compression, that portion of the powder which is immediately behind the bullet is consolidated to a degree approaching that attainable by. fusion'and that this degree of consolidation decreases toward the rear end of the firing chamber. g

It has been ascertained that it is not the degree of consolidation alone which accounts for the results flowing from the procedure of the present invention; that is to say, a charge of 5 Claims. (Cl. 164-05) powder can be compressed separately to the same degree to which it is compressed in the practice of the present invention and then placed in the firing chamber and the bullet arranged in front of it without making possible the development of a sufilcient projecting pressure. As a matter of fact, when the gun is loaded in thismanner, it is wholly inoperative, since the pressure developed is sufflcient only to push the bullet out of the barrel without any penetrating force.

By the practice of the present invention, on e the other hand, *greatly increased efliciengy of the powder can be realized. For example, the same penetration can be obtained by the prac-- tice of the present invention with one-third of the powder charge that is necessary when the previous practice of using mechanical restraining means on the bullet is resorted to. Thus, it appears that ognething occurs during the compression of th powder by the bullet, whether it be the establishement of an intimate adhesion between the powder and the walls of the ing chamber or thesetting up of a cementing layer between the bullet and the interior of the barrel, which accountsior .thaunexpectedresults. .7

attained. No attempt is here made to explain why the improved efficiency is secured.

It may be noted here that, for the practice of the present invention, it is preferred to use a fine-grained powder, particularly one which is fast burning. The greaterthe size of the grains of the powder, the less is the advantage realized by the procedure constituting the present invention.

As will be understood from the above discussion, the present invention makes possiblethe use of a single integral element, which constitutes both the barrel and the firing chamber. As a feature of this invention there is provided a readily replaceable firing filament which is not mechanically connected to the firing chamber barrel in place:

Fig.3 is a vertical section of the gun barrel showing the'position of the powder at the be-v ginning of the charging operation; and

Fig, 4 is a similar view showing the position of a bullet and the powder at an intermediate stage of the charging operation.

Referring to the drawings in detail, numeral I designates a gun body which, as is known, is ordinarily a long cylindrical bomb connected to the surface by a cable carrying electrical conductors and being provided with a plurality of wells 2 in which are arranged gun barrels. In this particular instance, the gun barrel 3 is a cylinder of suitable metal having a central recess 4 extending from its outer end nearly to its inner end, said central recess being connected to the other end of the barrel 3 by a passage 5 of smaller diameter which serves the purpose hereinafter Intermediate the ends of recess 4 is a shoulder 6 which separates the firing chamber from that portion of the recess which accommodates the bullet I. This shoulder plays an important part in the practice of the present invention since, by its location, the degree of the compression of the powder charge can be regulated so that any 7 pressure in the bore hole would serve to compress the powder charge to the point where it might not ignite and, if ignited, would not have its normal efliciency.

Arranged in the inner end of recess 4 is a metal stud 8 carried by a stem 9 which passes through the passage 5 and extends beyond the inner end of the barrel 3 where it makes contact with a flat conducting strip l which is insulated from the gun body I by insulating strips II and is connected to a conductor I2 which, in turn, is connected to a resistor l3 which is arranged in the firing circuit which is supplied by power arranged at the surface. The stem 9 has a smaller diameter than the passage and is held in spaced relation thereto and insulated from the walls thereof by packing rings.

The stud 8 is insulated from the gun barrel 3 by insulating packing I4 and has its inner face exposed to make contact with the prongs of a cotter pin l5 which passes through a pair of insulating disks l6 between which is arranged a metal disk II, the edges of which are preferably serrated and upturned to press resiliently against the wall of the firing chamber. The firing filament I8 is connected between the top of the cotter pin and the disk II. It may be noted here that the center portion of the disk is cut away so as not to come into contact with the cotter pin. The outer end of the pin 9 is surrounded by packing material l9 which constitutes a seal to prevent fluid from entering the firing chamber from the rear and holds the stem in spaced relation to the wall of passage 5.

As is shown, the gun barrel 3 is for the greater part of its length of a diameter such as to fit snugly in the well 2, while at its outer end it is of somewhat reduced diameter. A pair of diametrically opposed set-screws 20 are arranged in the gun body I with their ends adapted to thrust against the outer surface of the gun barrel 3 at a point where it has a reduced diameter in order to hold it in place. It will be understood, of course, that the gun barrel can be made of uniform diameter throughout its length and provided with recesses to receive the setscews.

Referring to Fig. 3, it will be noted that the first step in loading the gun barrel is to insert in place the small unit of disks carrying the cotter pin and firing filament. is then filled with powder. The bullet which is selected to fit the recess snugly is then inserted into the top of recess 4 and is pressed into place by any suitable press capable of exerting the desired pressure. For most operations it has been found that a small hand press is sufficient for this purpose. As previously stated, the shoulder 6 in the recess 4 is so located that the desired amount of compression of the powder will be attained when the bullet sets on the shoulder. In practice, it has been found that when recess 4 has a diameter of of an inch at its larger end and 1 g of an inch at its smaller end and is 2% inches deep, suitable projecting compression can be obtained by arranging a shoulder about midway between the ends of the recess. cation for the shoulder with different size guns can be ascertained by experiment. It is desirable to have a number of gun barrels of the same size, but with shoulders arranged at diflerent points for use of different powders and for different degrees of penetration.

If desired, the open end of recess 4 can be plugged by a rubber stopper. This is not necessary, however, because another feature of the present invention is that by the practice thereof the powder immediately behind the bullet is so compacted as to form a fluid-tight seal for the remainder of the powderchamber. While reference has been made herein to a bullet it will be understood that a coring device is also contemplated within the general term projectile."

The objects and advantages of the present invention having been thus described and illustrated, what is claimed as new and useful and is desired to be secured by Letters Patent is:

1. A well bore hole gun barrel comprising a metal body having an elongated recess therein having a sealed inner end, a projectile fitted into the open end of said recess, a powder charge compressed in situ in the inner end of said recess by said projectile said projectile being of a size to make a snug fit with said barrel and the compression pressure being of the order of that required to compress the powder in finely divided form to half its original volume, and a firing element in said powder charge.

2. A well bore hole gun barrel comprising a metal body having an elongated recess therein having a sealed inner end, a shoulder intermediate the ends of said recess, a projectile fitted into the open end of said recess and seated on said shoulder, a powder charge compressed in situ in the inner end of the recess by said projectile, said projectile being of a size to make a snug fit with said barrel and a firing filament in said powder charge.

electrical contact and a filament connected to 4 said metal portions arranged in said recess and a powder charge disposed around said filament The entire recess 4 The best 10- amenae and compressed in the inner end of said recess by said projectile.

4. A method for loading a gun barrel of a well bore hole gun which comprises filling said barrel with loose fine grained powder to a point where it occupies a volume considerably in excess of its firing volume, inserting a projectile into the open end of said barrel, and applying pressure to said projectile to compress said powder a predetermined amount said pressure being of the order of that sumcient to compress said powder to half the volume it originally occupied. 5. A method according to claim 4 in which a firing filament is first arranged in said barrel and is surrounded by said loose powder.

ROBERT R. THOMPSON. WHITMAN D. MOUNCE. 

